Moisture responsive control means



.BUHQ 5, R B D 2,748,687

MOISTURE RESFONSIVE CONTROL MEANS Filed Sept. 1, 1953 2 Sheets-he3t l snventor attorneys June 5, 1956 R. L. BALLARD 2348 687 MOISTURE RESPONSIVE CONTROL MEANS Filed Sept. 1, 1951 2 Sheets-Sheet 2 MOITURE RESPONSIVE CONTROL MEANS Robert L. Ballard, Detroit, Mich, assignor to General Motors Corporation, Detroit, Mich a corporation of Delaware Application September 1, 1951, Serial No. 244,823

10 Claims. (Cl. 98-4) This invention relates to moisture responsive control means, and more particularly to control means adapted to close an opening in an automobile body in the event of rain.

One feature of the invention is that it provides improved moisture responsive control means; another feature of the invention is that it provides control means comprising a moisture responsive switch mounted within the automobile body for controlling the operation of motor means therein; a further feature of the invention is that the moisture responsive switch is mounted below the opening in the body in a position to be struck by rain admitted through said opening; still another feature of the invention is that it provides a moisture responsive switch comprising spaced conductor members, insulating means supporting said conductor members, and a wetting agent on said insulating means; a further feature of the invention is that the moisture responsive switch is provided with an electric heating element positioned adjacent the insulating means for drying said insulating means while the switch is operative; yet another feature of the invention is that the insulating means comprises a Web formed of multifilament strands of a plastic material which is stain-resistant and highly absorbent and which resists abrasion; and still a further feature of the invention is that the wetting agent which impregnates the insulating web has the characteristic of concentrated ionization when wet.

Other features and advantages of the invention will be apparent from the following description and from the drawings, in which:

Fig. l is a fragmentary longitudinal section through the cowl ventilator in the front portion of an automobile body, the cowl ventilator being shown in solid lines in closed position and broken lines in open position; Fig. 2 is a fragmentary perspective view of the preferred form of moisture responsive switch of Fig. 1, parts being broken away to show underlying structure; Fig. 3 is a diagram of the electrical circuit for the moisture responsive control means; Fig. 4 is an enlarged detail view indicating the impregnation of the insulating web of Fig. 2 with a wetting agent; Fig. 5 is a top plan view of a modified form of moisture responsive switch; Fig. 6 is a longitudinal section taken along the line 66 of Fig. 5; and Fig. 7 is a fragmentary enlarged detail view of a portion of the structure shown in Fig. 6

Automobile bodies are provided with several openings which should be closed in the event of rain, but which it is often desirable to leave open during fair weather, for example, the front portion of the automobile body is usually provided with one or more cowl ventilators; closed body automobiles and convertibles are provided with windows; and convertible automobiles are provided with a movable top. The moisture responsive control means disclosed and claimed herein is particularly adapted to close such openings in the event rain enters the cowl opening, the windows, or the open top of a convertible type automobile.

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The moisture responsive switch disclosed and claimed herein is so constructed that a single drop of water or even the moisture of a very humid atmosphere will actuate it, and the preferred embodiment of the switch incorporates a heating element which is energized during the time the switch is closed to dry the switch and render it quickly usable again.

Referring now more particularly to the drawings, in Fig. 1 the front portion of an automobile body is designated as 10, said body carrying a windshield 11, the body portion 10 is provided with a cowl opening, and a movable closure member, or cowl ventilator 12, is provided for closing said opening. The cowl ventilator 12 is pro vided on its under side with a battle or deflector 12a, and the ventilator is connected by means of a link 13 with motor means for moving the ventilator 12 between the open and closed positions illustrated in Fig. 1. In Fig. 3 the motor means is illustrated as an electric motor 15, although it will be understood that other motor means, as for example, a hydraulic motor, may be the prime mover for the ventilator and said prime mover may be controlled by the electric motor 15.

The cowl opening is sealed by means of a weather strip 16 which is carried in a frame 17 supported on a mounting flange 18 which is secured, as by welding, to the under surface of the body 10. A peripheral frame 20 immediately below the cowl opening carries a screen 21 for preventing insects, gravel, etc., from entering the body through the cowl opening. Immediately below the screen 21 and extending from the frame 2'0 is a mounting bracket 22 which is welded to a supporting bracket 23 to provide a rigid mounting means for a moisture responsive switch designated generally as 25. The switch 25 is positioned below the cowl opening in a position to be struck by rain admitted through said opening.

While the invention is illustrated only in association with an automobile cowl ventilator, it will be understood, as pointed out above, that the control means may be utilized to close any opening in the automobile body, as for example, the top of a convertible automobile or the windows of a convertible or a closed automobile, and reference is made to the co-pending application of Louis P. Garvey, Karl A. Walter and Robert L. Ballard, entitled Vehicle Folding Top Structure, filed September 1, 1951, as Serial No. 244,784 for a disclosure of a con vertible top adapted to be operated by the improved moisture responsive means.

Fig. 2 shows the structure of the moisture responsive switch 25. An open topped casing 26 carries on its under side spacing brackets 27 and 28, which brackets may be bolted to the mounting bracket 22 as shown in Fig. 1. At the bottom within the casing is a phenolic insulator 30 covered by a glass cloth filler pad 31. An electric heating element designated generally as 32 comprises spaced parallel conductors 33 and 34 extending longitudinally at opposite sides of a thin strip of conductive rubber 35. The element illustrated is commercially obtainable under the trade name Uskon.

Above the heating element 32 is a web 36 of insulating material which is woven around a plurality of spaced parallel wires, alternate ones of which are electrically connected together. The electrically interconnected wires of one group are designated by the reference charactor 37 and are interconnected by means of a buss Wire 3701, and the electrically interconnected wires of the other group are designated by the reference character 38 and are electrically connected together by a buss wire 38a. The wires 38 are illustrated in Fig. 2 as being bent upwards, but it will be understood that this bending is done merely to show the construction of the device, and that in the device the two groups of wires are parallel throughout their length, being insulated from each other adjacent the buss wires 37a and 3841 by means of a ribbon of insulating material. Protective grid bars 26a are mounted across the open top of the casing 26.

The woven web of insulating material 36 preferably is of a plastic material which is stain-resistant, highly absorbent, which resistsabrasion, and which is mechanically strong. While various materials are suitable for this insulating web, a web woven of multifilament saran is preferred. This plastic material holds a dye with little fading, thus providing a pleasing appearance in the event the moisture responsive switch is mounted in plain sight within the automobile body. The material has excellent absorbency, particularly when used with a wetting agent, due to the capillary spaces between the fine threads of the multifilament saran. When the conductors 37 and 38 are woven in the woof of the web, the direction of moisture flow in these capillary spaces is perpendicular to the direction of extent of the conducting wires so that the wires may be electrically connected very quickly when the insulating material becomes wet. At the same time the wires are held apart by the threads of the warp so that a short circuit cannot occur.

In order tospeed the action of the moisture responsive switch and to make the switch more sensitive, the insulating material preferably is impregnated with a Wetting agent. The wetting agent should have the characteristic of concentrated ionization when wet so that the wetting agent acts as an electrolyte to improve the sensitivity of the moisture responsive switch. Many wetting agents are suitable for this purpose, and if desired a combination of wetting agent and electrolytic salt may be used. However, instead of using a salt I prefer to impregnate the web of insulating material with a saturated solution of a wetting agent which has the characteristic of concentrated ionization when in solution. A suitable material in powder form may be obtained under the trade name of Antaron Rl55. The powder may be dissolved in distilled waterto provide a concentrated solution, and the insulating web may be saturated with this solution and then dried. Fig. 4 shows diagrammatically the insulating web impregnated with a wetting agent.

The operation of the moisture responsive switch of Figs. 1 and 2 is illustrated in Fig. 3. A source of voltage may be the automobile battery, and a primary circuit is provided for connecting the battery to the motor 15. This circuit is formed by a lead 46 which extends from the ungrounded terminal of the battery to one terminal of the switch 47a of a power relay having a coil 47. The other terminal of the switch 47a is connected by a lead 48 to one terminal of the motor 15, the other terminal of said motor being grounded. A secondary circuit for connecting the source of voltage to the power relay coil is formed by a lead 49 which extends from the lead 46 to one terminal of the switch 50a of a sensitive relay having a coil 50. A lead 51 extends between the other terminal of the switch 50a and one terminal of a limit switch 52 which is operated by the cowl ventilator 12, said switch being open when the ventilator is closed and being closed when the ventilator is open. A lead 53 connects the other terminal of the limit switch 52 with one terminal of the power relay coil 47, the other terminal of said coil being grounded. The electric heating element 32 (shown schematically as a resistor) is connected between the lead 51 andground.

Atertiary circuit for connecting the source of voltage to the sensitive relay coil 53 includes the spaced conductors 37 and 38. This circuit is formed by a lead 54 which extends from the lead 46 to the buss wire 37a and lead 55 which connects the buss wire 33a with one terminal of the sensitive relay coil 50, the other terminal of said coil being grounded.

In one embodiment of the invention a 12-volt battery was used and the sensitive relay was a Sigma relay reage drop of .6 volt when energized.

Assuming switch 52 to be closed as shown, the power relay will not be energized because of the open sensitive relay switch 50a. in the event a single drop of water strikes the insulating web 36 of the moisture responsive switch the wetting agent will cause the water to spread between two adjacent wires 37 and 38, and some of the wettingagent will dissolve to provide an electrolyte and establish a current path between said two adjacent wires, closing a circuit through the sensitive relay coil 50 to energize this coil and close the switch 50a. Closure of switch 59a completes a circuit through the power relay coil 47, and at thesame time completes a parallel circuit through the heating element 32, which acts to dry the insulating web 36 and break the circuit between the wires 37 and 38. Energization of the power relay 47 causes the switch 47a to close, connecting the motor 15 with the battery 45 so that the ventilator 12 will be closed. When the ventilator is closed the limit switch 52 is opened, breaking the circuit to the power relay.

The construction of the moisture responsive switch 52is such that a single drop of water anywhere on the insulating web 36 will actuate the moisture responsive switch, and the sensitivity of the device is so great that it will be operated by the moisture of the atmosphere if the'relative humidity is of the order of 92% or more.

Figs. 5, 6 and 7 show a modified form of moisture responsive switch. An open topped casing "it? of aluminum or other conductive material is grounded, as indicated at 71. A peripheral insulating frame 72 of Bakelite or similar-material is mounted in'the open top of the casing by means of bolts 73. The frame '72 carries a grid of closely spaced wires, 75, these wires being electrically connected to one of the bolts 73. As shown in the Fig. 7, this electrical connection is provided by means of conducting washers 76 and 77, and the bolt 73 is insulated-from the casing 70 by means of the frame 72 at the top and by means of an insulating washer 78 at the bottom. A terminal lug '79 is mounted on the bolt 73 by means of nuts 80 and 81 The lug 79 maybe connected to one terminal of the coil 82 of a relay, the other terminal of the coil being connected through an On-Off switch 83 to a source of voltage designated as 84. The switch 82a of the relay has one terminal connected to the source of voltage 84 and the other terminal may be connected to motor means for operating a movable closure member, as for example, the cowl ventilator 12 of Fig. 1.

.In the operation of the switch, the relay coil 82 is energized through a circuit which includes a drop of Water spanning the space between the grid 75 and the casing 70. The grid wires are spaced from the casing a distance of the order of of an inch, and surface tension will cause a drop of water to bridge this space to close the circuitpath.

While I have shown and described two embodiments of my invention, it is subject to many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. Apparatus of the character described, including: an automobile having an opening therein; a movable closure member for said opening; motor means for moving said member between open and closed positions; a circuit for actuating said motor means; a moisture .respons ive switch mounted within said body and connected to said circuit for controlling the operation of said motor means and a wetting agent on said switch, said wetting agent-having the property of reducing the surface ten- SlOIl of water so that the water spreads across said switch.

2. In an automobile body having an opening therein, apparatus of the character described, including: a movable closure member for said opening; motor means for moving said member between open and closed positions; a circuit for actuating said motor means; a moisture responsive switch mounted within said body and connected in said circuit for controlling the operation of said motor means, said switch being mounted below said opening in position to be impinged upon by moisture admitted through said opening; and a wetting agent on said switch, said wetting agent having the property of reducing the surface tension of water so that the water spreads across said switch.

3. In an automobile body having an opening therein, apparatus of the character described, including: a movable closure member for said opening; motor means for moving said member between open and closed positions; a circuit for actuating said motor means; electromagnetic switch means connected in said circuit; a moisture responsive switch mounted within said body below said opening and connected to said electromagnetic switch for controlling the operation thereof; a wetting agent on said switch for dispersing moisture thereon into a thin film; and electric heating means positioned adjacent said moisture responsive switch and connected to said circuit.

4. In an automobile body having an opening therein, apparatus of the character described, including: a movable closure member for said opening; motor means for moving said member between open and closed positions; a source of voltage; a primary circuit for connecting said source of voltage to said motor means, said circuit including the switch of a power relay; a secondary circuit for connecting said source of voltage to said power relay, said secondary circuit including the switch of a sensitive relay; a tertiary circuit for connecting said source of voltage to said sensitive relay, said tertiary circuit including a moisture responsive switch comprising spaced conductor members, insulating means supporting said conductor members, and a wetting agent on said insulating means, said wetting agent having the property of reducing the surface tension of water so that the water spreads across said switch; and an electric heating element positioned adjacent said moisture responsive switch and connected to said secondary circuit.

5. A moisture responsive switch of the character described, including: spaced conductor members; insulating means supporting said conductor members; and a wetting agent on said insulating means, said wetting agent having the property of reducing the surface tension of water so that the water spreads across said switch.

6. A moisture responsive switch of the character described, including: spaced conductor members; a web of insulating material woven around said members and a wetting agent impregnating said web, said wetting agent having the property of reducing the surface tension of water so that the water spreads across said switch.

7. Apparatus of the character claimed in claim 6, wherein said wetting agent includes an electrolytic substance.

8. A moisture responsive switch of the character described, including: a plurality of spaced parallel wires, alternate ones of which are electrically interconnected; a web of insulating material woven around said wires, said web being formed of multifilament strands of a plastic material which is strain-resistant, highly absorbent and which resists abrasion; and a wetting agent impregnating the web, said wetting agent having the characteristic of concentrated ionization when wet and having the property of reducing the surface tension of water so that the water spreads across said switch.

9. A moisture responsive switch of the character described, including: an open topped casing; a plurality of spaced parallel wires in said casing, alternate wires being electrically interconnected; a web of insulating material woven around said wires, said web being formed of multifilament strands of a plastic material; a wetting agent impregnating the web, said wetting agent having the characteristic of concentrated ionization when wet and having the property of reducing the surface tension of water so that the water spreads across said switch; an electric heating element positioned closely adjacent said web in said casing; an insulating member in said casing below said heating element; and an open grill across the top of said casing.

10. A moisture responsive switch of the character described, including: an open topped casing of conducting material; a peripheral insulating frame; at least one mounting bolt of conducting material supporting the frame in said casing, said bolt being insulated from said casing; and a grid of wires mounted in said frame spaced from but closely adjacent the surface of said casing and connected electrically to said conducting bolt.

References Cited in the file of this patent UNITED STATES PATENTS 1,157,208 Conrad Oct. 19, 1915 1,285,986 Grafford Nov. 26, 1918 1,554,674 Herod Sept. 22, 1925 1,772,232 Van Guilder Aug. 5, 1930 1,791,151 Tarvid Feb. 3, 1931 1,928,472 Wilcox Sept. 26, 1933 2,048,439 Fairchild July 21, 1936 2,166,481 Baird July 18, 1939 2,283,083 Neubauer May 17, 1942 2,297,248 Rudolph Sept. 29, 1942 2,531,116 Donoghue Nov. 21, 1950 2,575,987 York et al. Nov. 20, 1951 2,617,972 Nutter Nov. 11, 1952 

